Electric storage batteries comprise essentially a partitioned container having a plurality of compartments each of which contains an electrochemically active cell element immersed in an electrolyte. Each cell element typically comprises a stack of alternating positive and negative polarity plates separated one from the other by a microporous dendrite growth suppressing sheet known as a separator. Each of these plates comprises a conductive current collector having an active material deposited thereon or therein depending on the nature of the battery (e.g., Pb-acid, Ni-Zn, etc.). The current collector supports its associated active material relative to the other plates in the element and conducts electrical current substantially uniformly throughout the plate. The current collectors each have a conductive tab, or the like, projecting therefrom for coupling that current collector to other current collectors from plates of like polarity within the cell element (e.g., for joining the positive polarity plates together). One well known means for electrically connecting the tabs of like polarity plates is a bar of metal, known as a plate strap, cast onto the tabs. Another well known means for connecting the tabs is a simple bundle of several plate tabs gathered together atop the cell element. Each cell element is electrically joined (e.g., in electrical series) through the intercell partition to a cell element in the next adjacent compartment. For this purpose, the plate connecting means (i.e., plate strap or tab bundle) typically includes an upstanding lug which is electrically joined to a similar lug on the adjacent cell element via an intercell connector passing through an aperture in the intercell partition. The intercell connector is sealed within the aperture to prevent leakage of electrolyte between the adjacent compartments. Canadian Pat. No. 1,103,307, for example: positions the intercell connector in a notch formed in the top of the intercell partition; places a mold over the lugs, notch and partition; and injects plastic into the mold to fill the notch, embed the intercell connector and encapsulate the lugs. However, it is not always possible to provide a tight seal between the upstanding lugs and the partition beneath the notch and between the mold and the lugs. Without a tight seal, the injected plastic thereby can squirt into the cell compartment and ruin the battery. The problem of sealing the mold to the lug is particularly acute where the lug is a bundle of plate tabs as any misalignment of the tabs provides an uneven surface along the sides of the lug. The problem is exacerbated even further when one attempts to consistently produce leak-free seals from one battery to the next on an automatic production basis considering the allowable manufacturing of the tolerance parts and the positioning thereof.
Accordingly, it is an object of the present invention to provide an improved, simple, reliable method of sealing the intercell connector and encapsulating the connector lugs on either side of the intercell partition which method substantially consistently eliminates leakage of injected plastic from the intercell connector region over a wide range of manufacturing tolerances.
This and other objects and advantages of the present invention will become more readily apparent from the detailed description thereof which follows.